The Electronic Health Information Laboratory (EHIL) at the Children\\\'s Hospital of Eastern Ontario (CHEO) Research Institute is looking for a Post?Doctoral Fellow responsible for research and development of secure multi?party computation and privacy preserving protocols for applications in the area of health information and medical research.

Candidates should have a Ph.D. in Computer Science, Computer Engineering, Mathematics, Engineering, or a related field, and a strong research track record with journal or conference publications in secure computation and/or privacy preserving statistics and data?mining.

This paper studies the distinctness of primitive sequences over Z/(M) modulo 2, where M is an odd integer that is composite and square-free, and Z/(M) is the integer residue ring modulo M. A new sufficient condition is given for ensuring that primitive sequences generated by a primitive polynomial f(x) over Z/(M) are pairwise distinct modulo 2. Such result improves a recent result obtained in our previous paper [27] and consequently the set of primitive sequences over Z/(M) that can be proven to be distinct modulo 2 is greatly enlarged.

The Random Oracle Model, introduced by Bellare and Rogaway, provides a method to heuristically argue about the security of cryptographic primitives and protocols. The basis of this heuristic is that secure hash functions are close enough to random functions in their behavior, and so, a primitive that is secure using a random function should continue to remain secure even when the random function is replaced by a real hash function. In the security proof, this setting is realized by modeling the hash function as a random oracle. However, this approach in particular also enables any reduction, reducing a hard problem to the existence of an adversary, to \\emph{observe} the queries the adversary makes to its random oracle and to \\emph{program} the responses that the oracle provides to these queries. While, the issue of programmability of query responses has received a lot of attention in the literature, to the best of our knowledge, observability of the adversary\'s queries has not been identified as an artificial artefact of the Random Oracle Model. In this work, we study the security of several popular schemes when the security reduction cannot ``observe\'\' the adversary\'s queries to the random oracle, but can (possibly) continue to ``program\'\' the query responses. We first show that RSA-PFDH and Schnorr\'s signatures continue to remain secure when the security reduction is non observing (NO reductions), which is not surprising as their proofs in the random oracle model rely on programmability. We also provide two example schemes, namely, Fischlin\'s NIZK-PoK \\cite{Fischlin05} and non interactive extractable commitment scheme, extractor algorithms of which seem to rely on observability in the random oracle model. While we prove that Fischlin\'s online extractors cannot exist when they are non observing, our extractable commitment scheme continues to be secure even when the extractors are non observing. We also introduce Non Observing Non Programming reductions which we believe are closest to standard model reductions.

Goldreich and Oren (JoC\'94) show that only trivial languages have 2-message zero-knowledge arguments. In this note we consider weaker, \\emph{super-polynomial-time} simulation (SPS), notions of zero-knowledge. We present barriers to using black-box reductions for demonstrating soundness of 2-message protocols with efficient prover strategies satisfying SPS zero-knowledge. More precisely, we show that assuming the existence of $\\poly(T(n))$-hard one-way functions, the following holds:

\\begin{itemize}

\\item For sub-exponential (or smaller) $T(\\cdot)$, \\emph{polynomial-time} black-box reductions cannot be used to prove soundness of 2-message $T(\\cdot)$-simulatable arguments based on any polynomial-time intractability assumption. This matches known 2-message quasi-polynomial-time simulatable arguments using a quasi-polynomial-time reduction (Pass\'03), and 2-message exponential-time simulatable proofs using a polynomial-time reduction (Dwork-Naor\'00, Pass\'03).

\\item $\\poly(T(\\cdot))$-time black-box reductions cannot be used to prove soundness of 2-message \\emph{strong} $T(\\cdot)$-simulatable (efficient prover) arguments based on any $\\poly(T(\\cdot))$-time intractability assumption; strong $T(\\cdot)$-simulatability means that the output of the simulator is indistinguishable also for $\\poly(T(\\cdot))$-size circuits. This matches known 3-message strong quasi-polynomial-time simulatable proofs (Blum\'86, Canetti et al\'00).

You will join a vibrant and growing team of security researchers at the Centre for Cybercrime and Computer Security (CCCS) at Newcastle University. The aim of the project is to address one of the grand challenges in the real world: how to develop an e-voting system that is secure, dependable and usable for future elections.

This is a five-year project, supported by the European Research Council (ERC) Starting Grant. The initial appointments will be three years. Further extension by another two years will be possible subject to the performance and available funding. The expected starting date is 1 March, 2013 (flexible)

To apply for the posts, you need to have a PhD in Computer Science, engineering or related discipline, with a solid background in security and an excellent track record. Expertise in one of the following areas is especially desirable: cryptography, dependability and usable security.

The Cryptography group within the Department of Computer Science has grown considerably in the last year and additional researchers are required in the following areas:

Analysis of “real world” protocols

Formal Methods applied to security protocols

Fully Homomorphic Encryption

Lattice Based Cryptography

Provable Security, i.e. Protocol and Mechanism design

Multi-Party Computation

You will hold a PhD, or expect to be awarded soon, and have experience in one of the sub-areas of cryptography mentioned above.

You will have a good level of analytical skills and the ability to communicate complex information clearly, both orally and through the written word together with the ability to use personal initiative, and creativity, to solve problems encountered in the research context.

Ideally, you will also have a strong publication record in top relevant venues, such as the IACR conferences and journal, ACM-CCS, IEEE S&P, ESORICS, etc

Appointment may be made at the Research Assistant (grade I) or Research Associate (grade J) level depending on skills and experience and will be for 2 to 3 years in the first instance.

Please Note: This is a “rolling advert” with a nominal close date only. Applications are welcome at any time and the timing of the selection process will be dependent on the applications received.

The Cryptography group within the Department of Computer Science has grown considerably in the last year and additional researchers are required in the following areas:

Analysis of “real world” protocols

Formal Methods applied to security protocols

Fully Homomorphic Encryption

Lattice Based Cryptography

Provable Security, i.e. Protocol and Mechanism design

Multi-Party Computation

You will hold a PhD, or expect to be awarded soon, and have experience in one of the sub-areas of cryptography mentioned above.

You will have a good level of analytical skills and the ability to communicate complex information clearly, both orally and through the written word together with the ability to use personal initiative, and creativity, to solve problems encountered in the research context.

Ideally, you will also have a strong publication record in top relevant venues, such as the IACR conferences and journal, ACM-CCS, IEEE S&P, ESORICS, etc

Appointment may be made at the Research Assistant (grade I) or Research Associate (grade J) level depending on skills and experience and will be for 2 to 3 years in the first instance.

Please Note: This is a “rolling advert” with a nominal close date only. Applications are welcome at any time and the timing of the selection process will be dependent on the applications received.